Mini 4WD Lightweight Gear Hole Drilling Jig for Improved Response - For Counter and Spur Gears By drilling holes (6 places) in the counter gear and spur gear, you can reduce weight. Response will also improve. For this, it is important to drill the holes evenly. Therefore, by using this jig, holes can be drilled evenly. Please use a 2mm drill for drilling. This listing is for the processing jig tool only. Please prepare a 2mm drill, fixing screws, and shaft. The usage is very easy, please purchase only if you understand. This product is manufactured using a 3D printer. There are no problems with its use, but the color may differ from the image or the shape may be slightly different, please understand. If you contact me, I can combine shipping with other items I have listed, so feel free to ask. Made by "Shimizu Seisaku Repair Workshop"